Furnace for color case hardening.

[lexington1]

I am thinking of trying my hand at color case hardening. Does anybody have any recommendations for a small furnace that would work for this? I've watched quite a few videos on how it's done and I feel confidant that I can do it, but any input on a small furnace would be most welcome. I am looking for something at least large enough that I could do like lock or maybe even action sized things in it.

[Greg Pennell]

This is the only heat treat furnace I have any experience with.  I’ve used this one for everything from knife blades, lock parts, pistol frames, and actions up to some rather large Marlin lever actions. I’ve had mine for about a dozen years with no issues so far.

Greg

https://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/color-case-hardening/ht-1-heat-treat-oven-and-color-case-hardening-kit-prod32302.aspx

[jerrywh]

I made my own and about 6 others. You can find the directions on the internet or Youtube. There is no cheap way.  You can buy an old ceramic kiln pretty cheap if you shop around.

[smart dog]

Hi,
Neycraft and other electric furnaces will work fine but one important piece is the controller.  Some come with no controller other than a standard manual dial but these manual ovens don't work like your kitchen oven where you set the temp and leave it.  With manual controls, you have to baby sit the temperature control for the entire time you are heat soaking the parts, which extends into hours.  For some you can buy external programmable controllers and for other ovens the controller is built in.  With a programmable controller, you can set the ramp up temperature rate, the holding temps, time for heat soak, and any ramp down temperature cycles if required.  I would stay away from any ovens with internal dimensions less than 9x9 and you will need to make or buy a crucible or metal box for the pack.  I buy bone and wood charcoal from Brownells, however, wood charcoal has been back ordered with them for months.

dave   

[Greg Pennell]

Dave, if you’re in need of good wood charcoal at much better prices than Brownells, google up Foy’s Pigeon Supplies. They sell very clean granulated hardwood charcoal, as a food supplement for pigeon breeders.  We used to get our bone charcoal from a supplier in Chicago...the name escapes me, I’ll have to go look up an old invoice...but likewise the price was much better than Brownells.

Greg

[smart dog]

Thanks Greg!!  I will definitely follow up.

dave

[flatsguide]

Greg, are you thinking of Ebonex in Chicago?
Richard

[Rwnblack]

Hi,

I use an old lab furnace from the 1970’s.  They were tossing it out so I helped them dispose of it!  I set it on its end so I can lower the steel box in from above.  Eventually I cut the door off and bought some fire brick for a cover. This way I made it deeper.  You can buy the parts to make a PID controller if you are some what handy with electrical.  Temp is crtical so a PID is needed.  I get my bone charcoal from ebonex in 50 lb boxes.  The wood charcoal is just hardwood lump charcoal I buy locally and grind with an old meet grinder.

[Mark Elliott]

I have an old Neycraft oven that I added a programmable (PID) controller to for about $100 in parts I bought off of Amazon and ebay.    I can set the temperature and leave it.    However,  the temperature can vary a good bit (50 degrees) from one part of the oven to another.   I generally try to put the part I am heat treating on an upside down crucible near the thermocouple.   That is really just a consideration for tempering.   As stated before, the Neycraft is about 9"x9" inside and I would not go any smaller than that.  That is just barely large enough to case harden a large lock plate.

[lexington1]

Thanks for the information! Those locks are beautiful! Weird question, but when you case harden the frizzens do you harden them before or after you do the color case harden on them? I've done quite a few frizzens with the Rifle Shoppe method and also the method that comes with the old Siler lock kits, and I've had pretty good success burning carbon into them with Kasenite and a torch, but the oven is something kind of off my radar at the moment. Have you had any issues the Brownells furnace Greg?

[Greg Pennell]

Greg, are you thinking of Ebonex in Chicago?
Richard

Yes!  That’s the place we got our bone charcoal from. I don’t do a large volume of CCH anymore, so haven’t bought any supplies in several years.  (If you’re frugal, like me, you can reclaim the used charcoal from your quench tank when you change the water...dry it out and it’ll work perfectly, again)

Lexington1, I’ve had zero problems with the oven or controller.  It’s been very dependable, and was used fairly heavily for the first several years of service.

Greg

[jerrywh]

I once ran a test on oven temps.  I found that the temp of ovens internally can very as much as 200 degrees from one section to another.  With thermocouples only 6 to 10 inches apart.  Especially from top to bottom.  Therefore I place a thermocouple in contact with the piece being treated or as close as possible.  Also most controllers cycle back and forth - 50° to + 50°.  So even with a thermocouple of a controller in contact with a piece the temp can very at least 50° one way or another.  maybe even as much as 200°   Controlers control temp exactly but only where the probe is located.  Try this if you have doubts.

[Rwnblack]

I have reused my charcoal as well.  The two lock above were cased with used charcoal but I added some new homemade wheat charcoal for the fun of it.  It takes lots of cooking to get the charcoal dry again, however.  I have a propane turkey frier I use to dry the charcoal.

Greg, are you thinking of Ebonex in Chicago?
Richard

Yes!  That’s the place we got our bone charcoal from. I don’t do a large volume of CCH anymore, so haven’t bought any supplies in several years.  (If you’re frugal, like me, you can reclaim the used charcoal from your quench tank when you change the water...dry it out and it’ll work perfectly, again)

Lexington1, I’ve had zero problems with the oven or controller.  It’s been very dependable, and was used fairly heavily for the first several years of service.

Greg

[44-henry]

My favorite furnace was a Johnson made gas furnace that I fitted a Honeywell digital controller to which I used when I lived in North Dakota. It was fast, accurate, and I didn't need to worry about burning out elements, something you will have to do eventually with electric. Also have used the Brownells and Neycraft electric furnaces. Currently use a large Paragon heat treatment oven.

[Tom Cooper]

If you are interested in muzzle loading parts only then you can get away with a smaller furnace, mine is 6"x8"x8" and will hold a full size lock plate and assorted parts etc. My only interest is the parts being hard, I could do larger parts with a redesign of my crucible , but again I don't muck with much beyond the muzzle loaders. Once the parts are packed my crucible is inverted and the works brought up to temp, then the box is slid off the lid and contents drop in at zero height above the water.

[lexington1]

That looks nice! I like the jig that you made to keep the lockplate from warping. I think I will copy that idea. I broke down and ordered a Brownell furnace. Do you color harden your frizzens?

[Tom Cooper]

If engraving them then yes as I anneal them first so they can be cut, That engraved lock was my first attempt at engraving and case hardening, and it shows ha.

Bigger is always better for tools such as furnaces, I was limited on funds when I purchased mine, but it has a digital control system and does a fantastic job for it's diminished capacity.

Enjoy

[Rwnblack]

I have casehardened the frizzens but I usually quench my parts below critical temp, 1333 F, to get the nicest colors but this leaves the frizzen too soft. For frizzens, I would go well above critical temp to make sure it is hard and produces hot sparks.